CVE 2018-11767
In Apache Hadoop 2.9.0 to 2.9.1, 2.8.3 to 2.8.4, 2.7.5 to 2.7.6, KMS blocking users or granting access to users incorrectly, if the system uses non-default groups mapping mechanisms.
See the 
CVE page on Mitre.org
for more details.
